Although in a fuel cell system, it is necessary to supply air according to the amount of electricity generated by the fuel cell, an electric generation requirement is likely to vary by SOC control on a battery or the like, and periodic variation sound from a compressor supplying air to a fuel cell stack is likely to be generated. Such variation sound, in particular, is likely to be recognized by a passenger, for example, when a vehicle is at rest with background noise low. The passenger feels such variation sound harsh to have an uncomfortable feeling.
On the other hand, in JP2006-179331A, the variation sound is masked by irregular noise such as in a radiator fan, and thus it is unlikely to be recognized by a passenger.
Other related literatures includes JP3895263B.